Actuators are used in a wide variety of commercial applications. Examples are opening and closing doors, raising and lowering loading ramps, positioning of aerodynamic edge flaps and tabs, and morphing structures, which are mechanisms on spacecraft or aircraft for actuating surfaces and other structural elements. Examples of doors are bay doors, instrument covers, and access panels. Typically, such actuators have to be relatively rugged to withstand use in thermally harsh environments, such as may be experienced in many commercial aircraft and spacecraft applications.
While present day electromechanical and mechanical actuators serve a useful purpose, it would nevertheless be desirable to provide an actuator which is capable of producing large torque and large deflection output in a much smaller, lighter, and more rugged package. SMA actuators have been developed that provide high torque capability, but their deflection range is limited . . . Such small and light weight actuators capable of providing high torque and even greater degrees of angular deflection would find significant utility in a wide variety of applications. Such applications would involve airborne and space based mobile platforms such as aircraft and spacecraft, where large, deployable surfaces are expected to be employed or controlled. Providing an actuator that is capable of producing a larger degree of angular deflection and/or torque at its output member, for a given weight and size, would also be highly beneficial in many applications where limiting weight and size are highly important design considerations. Such applications, again, are often found with airborne and space based mobile platforms, where reducing the weight of the aircraft or spacecraft is of paramount importance to designers. Providing an actuator that can achieve greater angular deflections and/or torques, but which is smaller and lighter in weight than presently available actuators offering similar performance characteristics, would be highly valuable to designers of various systems and/or platforms that employ actuators.